A massive landslide caused by a melting glacier in September of last year in Greenland resulted in a megatsunami that reached a height of 650 feet. Subsequently, there was an unexplainable tremor that rocked the earth for nine days.
Numerous scientists from all over the world have been attempting to identify this signal for the past year. According to a recent study published in the journal Science, they now have an explanation, and it serves as yet another caution that as global temperatures rise due to human activity, the Arctic is moving into “uncharted waters.”
According to University College London seismologist Stephen Hicks, a co-author of the paper, when seismologists began to feel vibrations through the ground back in September, some of them believed their instruments were broken.
He told CNN that it was more of a constant hum than the rich orchestra of high pitches and rumbles you might expect with an earthquake. The normal duration of an earthquake signal is a few minutes; this one lasts for nine days.
It was “completely unprecedented,” he added, and he was perplexed.
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The signal was tracked to eastern Greenland by seismologists, but they were unable to pinpoint its exact position. They so got in touch with colleagues in Denmark, who had learned about a tsunami that had been caused by landslides in the isolated Dickson Fjord area of the region.
To unravel the mystery, 68 experts from 15 different nations worked together for almost a year, sifting through data from satellites, on the ground, seismic activity, and tsunami wave models.
According to Svennevig, what transpired is known as a “cascading hazard,” and it all began with climate change brought on by humans.
Like many glaciers in the increasingly warming Arctic, the one at the foot of a massive mountain rising over 4,000 feet above Dickson Fjord has been melting for years.
The mountain grew more unstable as the glacier receded and ultimately fell on September 16 of last year, spilling enough debris and rock into the lake to fill 10,000 Olympic-sized swimming pools.
One of the biggest tsunamis in recent memory, the one that followed, caused a wave that was stranded in the crooked fjord for over a week, sloshing back and forth every 90 seconds.
The term “seiche” describes a phenomenon when a wave moves rhythmically in a confined space, resembling the sound of water splattering back and forth in a cup or bathtub. A scientist even attempted to replicate the impact in their bathtub but was unable.
Although seizures are commonly known, their prolonged duration was previously unknown to scientists. “People would have laughed at me a year ago if I had suggested that a seiche could last for nine days. It’s not possible,” Svennevig said, comparing the revelation to discovering a new hue in a rainbow out of nowhere.
The scientists discovered that the seismic energy present in the Earth’s crust originated from this seiche.
According to Hicks, this may be the first time that scientists have seen the effects of climate change “on the ground beneath our feet.” And nothing was safe; he said the signal took nearly an hour to get from Greenland to Antarctica.
The tsunami destroyed an abandoned military base and carried away centuries-old cultural heritage sites, but no one was hurt. However, this area of sea is on a frequently traveled cruise ship route. The authors of the study stated that “the consequences would have been devastating” if one had been present at the time.
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According to Svennevig, a landslide and tsunami of this magnitude had never before occurred in Eastern Greenland. According to him, it indicates that more regions of the Arctic are “coming online” for these kinds of climate events.
Landslide-triggered mega-tsunamis may grow more frequent and catastrophic as the Arctic continues to rise; over the past few decades, the region has warmed four times faster than the rest of the world.
Four people lost their lives and residences were destroyed in northwest Greenland in June 2017 due to a tsunami. According to Svennevig, the threat is not limited to Greenland; fjords with a comparable shape can be found in Alaska, some portions of Canada, and Norway.
Paula Snook, a landslide geologist at the Western Norway University of Applied Sciences who was not involved in the study, said that what happened in Greenland last September “once again demonstrates the ongoing destabilization of large mountain slopes in the Arctic due to amplified climate warming.”
She told CNN that recent rock avalanches in the Alpine and Arctic regions are “an alarming signal.” “The ground we are thawing has been frozen and frigid for many thousands of years.”
Lena Rubensdotter, a researcher at the Geological Survey of Norway who was not involved in the study, emphasized that there is still more to be learned about rock avalanches, which are also impacted by natural processes.
She did, however, note that it is “logical to assume that as the climate warms in Arctic regions, we will see more frequent rock collapses in permafrost slopes.”
According to Svennevig, the discovery of natural phenomena acting in ways that appear out of the ordinary illustrates how this region of the world is changing in ways that are not anticipated.
“This indicates that these systems are being forced into unfamiliar territory by climate change.”
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